Mr. Marcio Fonseca reports

GR SILVER MINING REPORTS INITIAL HIGH-GRADE RESULTS FROM PLOMOSAS MINE SAMPLING PROGRAM

GR Silver Mining Ltd. has released initial results of phase I of the new underground sampling program at the Plomosas mine in Sinaloa, Mexico. The program was designed around the following objectives:

• To model the recently mapped high-grade silver zones in the interior of the historic Plomosas mine, after completion of the March, 2023, National Instrument 43-101 mineral resource estimate (MRE);
• To collect metallurgical test work samples essential to define key parameters for implementation of a bulk sampling test mining program (BSTM) at the Plomosas mine (Table 1);
• To enhance the existing database of underground samples for improved reconciliation between the MRE and areas identified for a BSTM.

Sampling highlights

Initial highlights of the phase I Plomosas mine underground sampling program include:

• Chip mine face sample -- Level 883: 2,423 grams per tonne silver equivalent, consisting of 675 grams per tonne silver, 46.9 per cent lead, 4.5 per cent zinc and 0.54 gram per tonne gold (polymetallic hydrothermal breccia -- massive sulphide);
• Channel sample -- Level 833: 0.8 metre at 2,019 grams per tonne silver equivalent, consisting of 137 grams per tonne silver, 5.74 grams per tonne gold, 16.7 per cent lead and 18.2 per cent zinc (polymetallic hydrothermal breccia -- massive sulphide);
• Channel sample -- Level 950: 0.6 metre at 3,993 grams per tonne silver equivalent, consisting of 310 grams per tonne silver, 15.20 grams per tonne gold, 26.2 per cent lead and 10.2 per cent zinc (polymetallic hydrothermal breccia -- massive sulphide).

GR Silver Mining's president and chief executive officer, Marcio Fonseca, commented: "The success of our new geological model at the Plomosas mine, completed during the last six months, combined with detailed underground sampling, will be fundamental for the future development of engineering parameters to assess implementation of a bulk sampling test mining program in the underground mine. The current site has initial infrastructure and key permits in place, which can assist in any future mine and processing plant developments at the historic Plomosas mine."

The program will consist of two phases over the next four months, whereby phase I assesses metallurgical data collected to support engineering studies as part of the BSTM, and phase II will complete a much larger data set to help refine basic mining engineering and planning. Both phases of the program will support a decision to potentially implement a BSTM at the Plomosas mine before year-end.

The program leverages existing permits to operate at the Plomosas mine, providing full access to the 7.4 kilometres of underground development. Access to multiple areas for sampling has enabled a better identification of unmined regions with high-grade, continuous silver, gold, and base metal mineralization at various levels of the underground mine. Assay results from 21 samples collected at the chosen sites (Table 1) have returned high-grade results, with values of up to 3,993 grams per tonne silver equivalent. Multiple high-grade results indicate potential areas to advance phase II, targeting the collection of additional metallurgical data and progress toward the implementation of a BSTM in the Plomosas mine.

The areas selected for phases I and II of the program consist of material where mineralization is continuous, with evidence of silver, gold and base metal mineralization at concentrations attractive for a potential BSTM in early 2026. The BSTM will also require the construction of a demonstration processing plant on site, with details to be defined after the completion of phase II and associated engineering studies.

The company plans to continue investigating opportunities at the Plomosas mine, based on recent success, targeting the higher-grade silver zones in the MRE, which may support the implementation of a BSTM.

About the Plomosas project

The Plomosas project, including the recent high-grade silver discovery in the San Marcial SE area, is progressing in 2025 as an emerging high-grade silver district located in southern Sinaloa, Mexico. The Plomosas project, covering 43,187 hectares, benefits from mine infrastructure, road access and existing permits associated with past-producing historical mining sites. The district contains intermediate-to-low-sulphidation epithermal silver and gold mineralization, hosted in hydrothermal breccias and veins. Recent success in exploration and drilling has delineated wide, high-grade, shallow hydrothermal breccias in the San Marcial area, including the SE area discovery, where stepout drilling is progressing in 2025, aiming for continuous resource growth. At the historical Plomosas mine, where a subsidiary of Grupo Mexico operated the underground mine from 1985 to 2000, exploratory and metallurgical programs are being conducted to support future decisions regarding the implementation of a BSTM.

Quality assurance/quality control (QA/QC) procedures

The company has implemented QA/QC procedures, which include the insertion of blank, duplicate and standard samples in all sample lots sent to SGS de Mexico SA de CV laboratory facilities in Durango, Mexico, for sample preparation and assaying. For every sample with results above silver greater than 100 parts per million (overlimits), these samples are submitted directly by SGS de Mexico to SGS Canada Inc. at Burnaby, B.C. The analytical methods include four-acid digestion and inductively coupled plasma optical emission spectrometry, with lead fusion fire assay and a gravimetric finish for silver above overlimits. For gold assays, the analytical methods are lead fusion and atomic absorption spectrometry, lead fusion fire assay, and gravimetric finish for gold above overlimits (greater than 10 parts per million).

Qualified person

The qualified person under National Instrument 43-101, Standards of Disclosure for Mineral Projects, for this news release is Marcio Fonseca, PGeo, president and chief executive officer for GR Silver Mining, who has reviewed and approved its contents.

About GR Silver Mining Ltd.

GR Silver Mining is a Canadian-based, Mexico-focused junior mineral exploration company engaged in cost-effective silver-gold resource expansion on its 100-per-cent-owned assets, located on the eastern edge of the Rosario mining district, in the southeast of Sinaloa state, Mexico. GR Silver Mining controls 100 per cent of the Plomosas project, including the former Plomosas underground mine and wide, high-grade silver-mineralized zones at the San Marcial area. Recent discoveries in the 78 square kilometres of highly prospective, advanced-stage exploration concessions position the company well for resource expansion at the Plomosas project.

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